"We don’t get a chance when making a game to think about the next one until we are done actually making that first game. When we finished Modern Warfare 3, we had this big brainstorming session that lasted for weeks. Everybody gets to come up with ideas of what we want to do, not just what game we want to do, but moments in games.

We all really knew we wanted to continue making Call of Duty. We could have done something else, but we wanted to make Call of Duty, and we wanted to create a new universe, or a new story at least. We wanted new characters and new experiences.

The easy thing would have been – as we had finished the arc of Modern Warfare 1, 2 and 3 – to start a new arc within that same universe. That was the first step. But due to a lot of the changes we wanted to make with this new world, it really dictated out that we needed to make something that wasn’t Modern Warfare."

- Call of Duty: Ghosts executive producer Mark Rubin

I am glad they are shifting away from releasing a new Modern Warfare every year, it was getting a bit old, don't you think?